Yunzi mushrooms, Abiraterone, Onco-vaccines – new methods against prostate cancer

Prostate cancer is one of the most commonly appearing cancers. 11% of cancers in men are those linked with prostate neoplasm. The disease begins inconspicuously: frequent difficulties with urination that suggest benign prostatic hyperplasia. The development of prostate cancer can lead to death (9% of deaths from cancer. Prostate neoplasm leads to dangerous outbreaks of metastases within the liver, lungs or brain. Recently noticed correlation between infection with XMRV might be associated with the development of prostate cancer, but still the main factors of development are genetic and racial predispositions and a diet rich in saturated fatty acids, protein and cholesterol. That is why every man should carefully observe his body and should not hesitate to contact the physician if having any doubts, before it is too late.

The treatment of prostate cancer, depending on the severity involves surgery, radiotherapy or chemotherapy. Because the tumor is strictly hormone-dependant and its development relies on the level of male hormones, prostate cancer treatment involves also androgen blockade. With the help of hormone blockers testosterone levels decrease in both cells of testicles and at the pituitary and hypothalamus level. In patients with advanced prostate cancer, radical prostatectomy is performed, whereas in less urgent cases, one can limit the operation to a laparoscopic surgery and radiotherapy. The initial hormonal therapy improves the efficiency of both surgery and radiotherapy, because it causes partial regression of the tumor, enabling precise removal of the neoplasm, or reducing the area of ​​a tissue block assigned to radiotherapy. The level of PSA is a good indicator of the effectiveness of treatment and it should be decreasing up to 20 months after treatment.

Contemporary hormonal therapy, thanks to which the effectiveness of treatments grows significantly may include surgical castration (ie orchideoktomy), use of hormonal antiandrogens, estrogens, adrenal steroid hormones synthesis inhibitors or the use of GnRH analogues. In over 60% of cases the hormonal therapy appears to inhibit the progression of cancer very effectively. But the price to be paid is not low. Numerous side effects discourage its use both as monotherapy and adjunctive therapy: decreased libido, gynecomastia, loss of facial hair, change of body shape and erection problems, as well as cardiovascular complications raise concerns among both patients and physicians. Besides, there is a problem of cancerous cells resistance to hormones in the late stage of development. The cells appear to be insensitive even to high doses of estrogens. This follows from the fact that the genes encoding hormone receptors are turned off in the late stage development of cancer cells (by the means of hypermethylation).

These drawbacks eager the scientists to search for other ways to combat prostate cancer. The last achievement is an introduction of new measures of treatment. Abiraterone acetate – a new drug (to be known Zytiga) acting as an inhibitor of CYP-17 enzyme (strictly involved in the production of testosterone). The drug is particularly recommended for patients with prostate cancer resistant to castration. Despite the exorbitant price (single treatment costs approximately 40 000 dollars) a drug is yielding promising results by extending the lives of patients (according to the third phase of clinical trials by an average of 4 months). The effectiveness of the drug during the research has been so high that the control group has been called off. It was unethical to deny half of the patients the effective drug – so all the volunteers soon received the test pill. Shortly it became clear that PSA levels decreased after the treatment and the tumors reduced their volume. The combination treatment with steroids caused the extension of patients’ lives by almost 14 months. Currently, tests looking for a similar efficacy in the fight against breast cancer are being conducted.

Another discovery of the past several months is a substance found in Yunzi mushrooms (Coriolus versicolor) – Polisacharopeptyd (PSP). Asian culture used the mushrooms in traditional medicine for many centuries as a drug stimulating the immune system. Studies conducted on mice have shown that the PSP is able to prevent the development of prostate tumors in almost 100% rate, limiting the growth of cancer stem cells. In Japan, this drug is already used as an adjuvant in the treatment of gastrointestinal neoplasm.

The latest achievement of British scientists from the Mayo Clinic is the vaccine based on the antigens located on the surface of prostate cancer cells. This allows the elimination of lesions in the prostate gland without unnecessary damage to the surrounding tissue. The body is stimulated to the effective elimination of abnormal cells. Studies in rodents treated with human vaccines offer promising results and minimal side effects. The vaccine has so far proved to be useful in treating prostate cancer and melanoma.

Written by: Maria Bilińska




Source:

1. “FDA approves Zytiga for late-stage prostate cancer”. Press Release. U.S. Food and Drug Administration. 2011-04-28.
2. http://www.mayoclinic.org/news2011-rst/6322.html
3. http://www.zytiga.com/
4. http://cancerguide.org/psk.html
5. Abiraterone and Increased Survival in Metastatic Prostate Cancer; Johann S. de Bono, M.B., Ch.B., Ph.D., Christopher J. Logothetis, M.D., Arturo Molina, M.D., Karim Fizazi, M.D., Ph.D., Scott North, M.D., Luis Chu, M.D., Kim N. Chi, M.D., Robert J. Jones, M.D., Oscar B. Goodman, Jr., M.D., Ph.D., Fred Saad, M.D., John N. Staffurth, M.D., Paul Mainwaring, M.D., M.B., B.S., Stephen Harland, M.D., Thomas W. Flaig, M.D., Thomas E. Hutson, D.O., Pharm.D., Tina Cheng, M.D., Helen Patterson, M.D., John D. Hainsworth, M.D., Charles J. Ryan, M.D., Cora N. Sternberg, M.D., Susan L. Ellard, M.D., Aude Fléchon, M.D., Ph.D., Mansoor Saleh, M.D., Mark Scholz, M.D., Eleni Efstathiou, M.D., Ph.D., Andrea Zivi, M.D., Diletta Bianchini, M.D., Yohann Loriot, M.D., Nicole Chieffo, M.B.A., Thian Kheoh, Ph.D., Christopher M. Haqq, M.D., Ph.D., and Howard I. Scher, M.D. for the COU-AA-301 Investigators; N Engl J Med 2011; 364:1995-2005 May 26, 2011
6. Polysaccharopeptide enhances the anticancer activity of doxorubicin and etoposide on human breast cancer cells zr-75-30 International Journal Of Oncology 32: 689-699, 2008; Jennifer Man-Fan Wan, Wai-Hung Sit And Jimmy Chun-Yu Louie
7. Luk S-U, Lee TK-W, Liu J, Lee DT-W, Chiu Y-T, et al. (2011) Chemopreventive Effect of PSP Through Targeting of Prostate Cancer Stem Cell-Like Population. PLoS ONE 6(5): e19804. doi:10.1371/journal.pone.0019804

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